Update e-mail for Kei Kebreau.

Update e-mail for Kei Kebreau.

* .mailmap: Map kei@openmailbox.org to current address.
* gnu/local.mk: Replace kei@openmailbox.org to current address.
* gnu/packages/backup.scm: Likewise.
* gnu/packages/calendar.scm: Likewise.
* gnu/packages/check.scm: Likewise.
* gnu/packages/compression.scm: Likewise.
* gnu/packages/documentation.scm: Likewise.
* gnu/packages/emacs.scm: Likewise.
* gnu/packages/fltk.scm: Likewise.
* gnu/packages/freedesktop.scm: Likewise.
* gnu/packages/game-development.scm: Likewise.
* gnu/packages/games.scm: Likewise.
* gnu/packages/gnome.scm: Likewise.
* gnu/packages/gnustep.scm: Likewise.
* gnu/packages/gtk.scm: Likewise.
* gnu/packages/hexedit.scm: Likewise.
* gnu/packages/image.scm: Likewise.
* gnu/packages/maths.scm: Likewise.
* gnu/packages/music.scm: Likewise.
* gnu/packages/xfce.scm: Likewise.
* gnu/packages/python.scm: Likewise.
* gnu/packages/tcl.scm: Likewise.
* gnu/packages/textutils.scm: Likewise.
* gnu/packages/video.scm: Likewise.
* gnu/packages/w3m.scm: Likewise.
* gnu/packages/web.scm: Likewise.
* gnu/packages/web-browsers.scm: Likewise.
* gnu/packages/patches/wmfire-update-for-new-gdk-versions.patch: Likewise.